**2. Materials and Methods**

#### *2.1. Study Area*

Jiangjin District of Chongqing is located in southwestern Chongqing, adjacent to Guizhou Province to the southeast and Sichuan Province to the west and southwest (Figure 1). The geographical coordinates are between 105◦49 –106◦38 E and 28◦28 –29◦28 N. Jiangjin District has a total area of 3218 km2, with five subdistricts and 25 towns. The terrain of Jiangjin District descends gradually from north to south to the Yangtze River Valley, with hills and low mountains in the north and middle and mountainous areas in the south. It has a subtropical humid monsoon climate, with a mild climate and abundant precipitation. The main disasters are high temperature, drought, low temperature and rain, hail and so on. At the end of 2019, the forest area in Jiangjin District reached 16.6 × 104 hm2, and the forest coverage rate reached 51.8%. In 2019, the regional GDP of Jiangjin District was 103.67 billion yuan, and the per capita GDP reached 74,452 yuan. At the end of 2019, Jiangjin District had a permanent population of 1.398 million, and the urbanization rate of permanent residents was 69.76%.

As the Chinese government vigorously promotes coordinated regional development, the location advantages and development opportunities of Jiangjin District have become increasingly apparent. The construction of the Chengdu-Chongqing Twin Cities Economic Circle is an important part of the overall national regional development strategy. Jiangjin District is responsible for the construction of the western (Chongqing) Science City Jiangjin area in the construction of the Chengdu-Chongqing Twin Cities Economic Circle. Therefore, it is the vanguard of Sichuan-Chongqing cooperation. In the spatial pattern of the development of the One District and Two Clusters of cities and towns in Chongqing, Jiangjin District is an open new city of science and innovation, a new industrial area, and a cultural and tourist attraction in the main urban area, so it is a leader in the development of the western region of Chongqing. In addition, Jiangjin District is also a pioneering area for the co-urbanization of the main urban area of Chongqing. Obviously, the superposition of many strategies has brought unprecedented development opportunities to Jiangjin District. However, Jiangjin District is located in the upper reaches of the Yangtze River and at the

end of the Three Gorges Reservoir, and it is responsible for the construction of the ecological barrier in the Three Gorges Reservoir and the ecological protection of the upper reaches of the Yangtze River. In short, in the context of multiple strategic development opportunities and ecological protection, the question of how to optimize the PLES to provide a great space guarantee both for economic development and to strengthen ecological protection has become a key issue that urgently needs to be resolved in the territorial space planning of Jiangjin District.

**Figure 1.** The study area: (**a**) the location of Jiangjin District in Chongqing; (**b**) land use status of Jiangjin District in 2018. Note: Based on the standard map (scale 1:48 million) with the approval number of GS (2019) 1823 on the standard map service website, the base map has not been modified.
